1. Preheat your oven to 180C/fan 160C/gas 4, and prepare the vegetables: trim the ends from the aubergine, courgette and squash, and, with a mandolin, adjustable-blade slicer, or very sharp knife, slice them into pieces approximately 1mm thick. As carefully as you can, trim the ends off the red pepper and remove the core, leaving the fl esh intact, like a tube. Thinly slice crosswise. Thinly slice the onion as well.

2. Spread the tomato purée into a large baking dish. Stir in the onion slices, minced garlic, 1 tablespoon of the olive oil, a few pinches of salt, and a pinch of pepper flakes. Arrange the slices of aubergine, courgette,
yellow summer squash and red pepper so that they overlap, with just a smidgen of each fl at surface visible. The pepper will give you the most trouble, because it’s probably bigger in diameter than the other vegetables, but whether it fans prettily or not, it will bake nicely. You might not need all of your vegetables. Drizzle remaining tablespoon of olive oil over the vegetables and sprinkle with thyme. Cover dish with foil, and bake for 45 minutes, until vegetables are almost completely fork-tender.

3. Meanwhile, split your sub rolls. Once the 45 minutes are up, increase oven setting to 220C/fan 200C/gas 7, remove foil from the baking dish, and bake, uncovered, 15 minutes more. On the other rack, place your sub rolls on a tray to toast for 5–10 minutes.

4. A long, thin angled spatula, like a palette knife, is best for serving here. Carefully slide it under one section of the fanned vegetables, and slide it on to the bottom half of a toasted roll. Keep adding sections until you have covered the bread, and then repeat this so that you have a second layer of fanned vegetables. Scoop up any oniony sauce that was left beneath the vegetables, and lay it over the sub. Close each sub with the top half of the roll, cut into manageable lengths to eat, and serve.